Preheaters for heavy fuel oil



March 28, 1961 O. LEACH PREHEATERS FOR HEAVY FUEL OIL Filed Sept. 1'?, 1.956

IN VEN TOR. ORP/N l5/4CH BY /4 TT/PNEX I States Patent 1 PREHEATERS FOR HEAVY FUEL OIL Orrin Leach, 172-90 Highland Ave., Jamaica, N.Y.

Filed Sept. 17, 1956, Ser. No. 610,291

5 Claims. (Cl. 158-36) This invention relates to fuel oil preheaters and, more particularly, to preheaters adapted for use in connection with oil fired hot water heating systems.

Since it has been found that the proper combustion of heavy fuel oil depends upon the temperature of the oil, various types of systems have been proposed to heat such oil before being fired in a furnace. When the oil is cold, it becomes so thitck that it does not readily flow through the supply lines and in some cases actually blocks the passage of oil therethrough even under very high pressures. This makes it quite diii'icult to maintain a constant or proper flame in the furnace and increases wear on the mechanical parts of the system. Certain ones of the systems proposed for overcoming these difficulties have relied upon electrical or gas heater units disposed adjacent to adjacent to certain parts of the fuel oil supply line to heat the oil as it flows towards the burner, but these do not uniformly heat the oil so as to maintain the oil flowing to the burner at a substantially constant temperature so that uniform control of the ame cannot be maintained. Other systems have suggested heating the oil by various types of convection currents, but the convection medium must first be heated before it can be used to heat the fuel supply, thereby requiring additional time and supervision. In the aforementioned types of systems, since constantly changing ambient temperature conditions effect the viscosity inthe oil in the supply line, each such change also requires a change in the controls of the heating system, thereby increasing costs and decreasing eiiiciency.' An object of this invention, therefore, is to provide a fuel oil red heating system that is simple in construction, eiiicient in operation, and which will overcome all of the aforementioned diiculties.

Another object of this invention, is to provide a substantially automatic preheater system for fuel oil red furnaces that is operative to supply fuel oil to the burners at a substantially constant temperature regardless of ambient temperature conditions.

A still further object of this invention is to provide an automatic preheater system for o-il red furnaces that is equally efficient during summer conditions where it is only necessary to fire the furnaces in order to heat water, as well as being efficient during the winter months when the furnace isfalso` required to sup'ly heat to the room heaters.

Another object of this invention, is to provide a preheater system for fuel oil lines wherein the fuel oil supply j lines are heated along with the fuel oil return lines.

Still a further object of this invention is to provide an auxiliary preheating -apparatus for oil fired furnaces that is operative to initiate operation of the furnace after long periods of idleness.

Alll of the foregoing and still further objects and advantages of this invention, will become apparent from a study of the following specification, taken in connection with the accompanying drawing, wherein:

Figure 1 is a diagrammatic view of a fuel oil preheating ralice include a vertically disposed tubular housing 12 that is connected to a horizontally disposed tubular housing 13 by means of a tubular elbow section 14. The upper extremity of the vertical section 12 is provided with an enlarged circular ange 16 that is adapted to be placed in abutting engagement with a corresponding circular flange 17 of the lower bell-shaped end 33 of a reducer coupling, such as by bolts 18. The lower extremity of the vertical section is provided with a similar enlarged circular flangel 20 that is adapted to be secured in abutting engagement with a corresponding circular flange 21 of the elbow section 14 such as by bolts 23. The other end of the elbow is provided with a circular flange 24 that is adapted to be secured in abutting engagement with a similar enlarged 1 ange 25 of the horizontal section 13, by means of bolts line 3S of substantially reduced cross-sectional area than the fuel line 31, is received within the vertical stem 30 of` the reducer coupling and communicates with the tank return line 39 disposed within the vertical section 12 of the preheater by means of a port 40 extending through the abutted flanges 16, 17. Except for the ports 35, 40,

the flanges 16, 17, effectively seal the upper extremity of thel vertical section 12.

The delivery line 34 extends downwardly through the interior of the vertical section 12, and into the elbow and horizontal sections of the preheater assembly, from which it extends outwardly through a port or other suitable outlet 43 into a connecting line 44 having a manually-operated shutoff valve 45 associated therewith. The delivery lineY then communicates with the inlet side 46 of a screen type strainer assembly 47 that is disposed within a heater jacket 49 which has an opening 50 in abutting engagement with the outer extremity of the horizontal p-reheater section 13. The outlet 51 of the strainer communicates with an outlet line 52 that has a thermometer 53 and positive drive fuel pump 54 associated therewith and terminating with its engagement with one side of a three-way fitting 56. One side of the fitting 56 is provided with an inlet line 57 which communciates with the burner 10i) of the furnace assembly 101. This line 57 includes a dial-type pressure gauge 58 and la magnetic relay valve 59 that is effective to automatically discontinue the supp-ly of fuel to the burner. The third connection to the fitting 56 is provided with a return line 61 which includes a manually adjustable pressure control valve 62 and which is received within the horizontal section 13 through a fluid-tight port 63 and communicates directly with the tank return line 39 means of an inlet port 68. An outlet connecting line 69 communicating with the lower extremity of the strainer j,

jacket 49 connects with the inlet side o-f a motor-driven circulating pump 7tlg the outlet side of which has a return line 7l connected thereto which at its other extremity communicates with the interior of the hot water boiler tank 67 by means of an inlet port 72. The flow ofV waterfrorn thetank 67 into the upper end of the vertical section 12, downwardly through the elbow, horizontal, and strainer jacket sections is controlled by an aquastat 73 having a temperature responsive element 74 disposed within the lower section of the strainer jacket. The aquastat is operative to control the supply of current to the circulating pump 7@ from a source 75 in response to the temperature of the water within the jacket.

In operation, it is iirst to be assumed that the furnace has been operated and that it has heated a substantial quantity of water that is stored within the hot water tank 67. While the burner may not be tiring continuously, the water contained within the tank 67 will remain heated for a considerable period of time. This water is normally circulated through the connected sections of the preheater unit le by means of the circulating pump 7l),

which circulation may be continued or interrupted by the aquastat 73, so that the temperature of the water within the entire preheater may be maintained at a substantially constant temperature. The fuel oil is delivered to the burner through the delivery line 3d that passes through the preheater and into association with the strainer 47. Oil passing therefrom is in a substantially thin state so that the positive drive pump ft is effective to pump it into the burner of the furnace. ln the event that the magnetic oil valve 59 prevents the ow of oil to the burner, the oil is `returned through the return line 61, past the pressure control valve 62 and into the tank return line 3g which passes through the heated water contained within the preheater and out through the tank feedline 38 back into the oil tank .'52, The pressure control valve 62 is adjusted to maintain any desired pressure from that point forward to the burner, so as to eiectively maintain the pressure in that line 57 at any desired amount. it is to be noted that the fuel oil is passed initially through the preheater by means of the delivery line 34 and the overflow is passed back to the preheater by means of the tank return line 39 so that the oil feeding back into the tank is also at a high temperature which contributes to the preheatiug of the fuel oil within the tank 32. Of course, when the furnace is tired additional water in the hot water tank 67 will beheated so that when the furnace is temporarily not being tired and the flow of fuel through the respective supply lines is discontinued, the preheater will be effective to maintain a supply of oil at a desirable operating temperature for the next tiring cycle.

In order to facilitate the start of the furnace on very cold days after a long period of idleness, an auxiliary or starting preheater 78 is provided wherein a small tank or reservoir 79 having a iioat-type fuel-quantity gauge 81 and a vented filler cap 82 at the upper end thereof has a gas burner 34 `disposed beneath the tank. This burner is adapted to be supplied with a gas type fuel through a line 8S having a manually operable shutoff valve 86 associated therewith. A supply of fuel oil 88 is adapted to be delivered to the interior of the reservoir 79 by means of a line 89 that is in communication with the return line 61 and which is controlled by manually operable shutoff valve 90. The outlet line 92 leading from the tank 79 communicates with the outlet line 52 and positive drive pump 54, the flow of oil through the outlet being controlled by a manually-operated shutotf valve 93. In operation of this starting preheater, it may be assumed that the entire heating system has been shut down for aprolonged period of time so that no hot water is available in the tank 67 to heat the incoming supply of fuel oil in the manner hereinbefore described. In this case, the burner 84 is manually ignited so as to heat a small quantity of oil 88 within the tank which has been left there from prior use, after which, the oil is permitted to draindown into the outlet line 52 and into engagement with' the positive drive pump` 54, whereupon it is lluid enough to be delivered to the burner inlet valve 57. The flow of oil is continued long enough to heat a suicient quantity of water within the main water tank 67, after which the automatic preheater system is effective to maintain the continued operation of the systern. Then, the reservoir 79 may be lled with a new quantity of oil by opening the valve 96, so that a supply of oil is always maintained therein. It is to be understood, that this auxiliary preheater is necessary only after prolonged periods of burner shutdown, the hot water preheater system being effective to maintain the fuel oil line at a substantially constant temperature during the winter months and during intermittent summertime operation.

While this invention has been described with particular reference to the specilic form shown in the drawing, it is to be understood that such is not to be construed as imparting limitations upon the invention, which is best defined by the claims appended hereto.

I claim:

l. A fuel oil supply system for -fuel oil tired furnaces comprising, in combination, a hot water tank, a fuel oil supply tank, a fuel pump having an inlet and an outlet for delivering fuel to a burner, a Vfuel oil delivery line adapted to deliver oil from said tank to said pump, a fuel oil preheater associated in heat transferring relationship with said delivery line between said tank and said pump, said -hot water tank including duct means for supplying hot water heat to said preheater, a return line connected at one extremity to said delivery line on the outlet side of said pump and at the opposite extremity to said fuel oil supply tank, the intermediate portion of said return line passing in heat transferring relationship through said preheater, an auxiliary fuel oil tank having a fuel oil supply line communicating with said return line, an inlet line for delivering fuel from said auxiliary tank communicating with said inlet of said pump, and means for supplying heat to said auxiliary tank independently of said heat supply means for said preheater.

2. A fuel oil supply system as set forth in claim l, wherein said prcheater comprises a hollow closed housing. said fuel oil delivery line passing through the interior of said housing, and means for circulating a heating iluid within said housing.

3. A fuel oil supply system as set forth in claim 2, said fluid comprising water contained in said water tank. and said circulating means comprisingv a pump and counecting lines for force circulating said water through said housing and back to saidV Water tank.

4. A fuel oil supply system as set forth in claim 3, wherein said circulating means further comprises power supply means for energizing ysaid circulating pump, and temperature responsive means associated with the interior of said housing adapted to energize said circulating pump in response to predetermined temperature conditions of water within said housing.

5. A fuel oil supply system comprising, in combination, a fuel oil supply tank, a fuel pump having an inlet and an outlet for delivering fuel to a burner, a fuel oil delivery line adapted to ydeliver oil from said tank to said pump, a fuel oil pre-heater associated in heat transferring relationship with said delivery line between said tank and said pump, a hot water tank including duct means for supplying hot water heat to said preheater, a return line connected at one extremity to said delivery line on the outlet side of said pump and at the opposite extremity to said fuel oil supply tank, the intermediate portion of said return line passing in heat transferring relationship through said pre-heater, an auxiliary fuel tank havingy a fueloil supply line communicating with said return line, an inletline for` delivering fuel from said auxiliaryy tank communicating with said inlet of said pump, and means ,for4 supplying heat to said auxiliary tank independentlyof .said heat supply means for supplying heat to said pre-heater, said pre-heater comprising a closed hollow housing enclosing a portion of said fuel oil delivery line therewithin, circulating means for circulating hot water within said housing from said hot water tank duct means, said circulating means comprising a pump and connecting lines for force circulating water through said housing and back to said hot Water tank, power supply means for energizing said circulating pump, and temperature responsive means within the interior of said housing controlling ene-rgization of said circulating pump inyresponse to changes in the temperature of the water circulated within said housing between predetermined upper and lower References Cited in the le of this patent UNITED STATES PATENTS 1,085,160 Reichenbach I an. 27, 1914 6 Winslow Dec. 6, Gibson Nov. 23, Smith Jan. 3, Macrae et al. June 14, Johnson May 14, Bachmann Mar. 18, Brunner May 29,

FOREIGN PATENTS France Nov. 18, Great Britain Jan. 17, Switzerland July 15, 

